Atomically precise two-dimensional (2D) semiconductor nanoplatelets (NPLs) are found to be promising materials for next-generation optoelectronic devices due to their excellent optical properties. However, energy loss through phonon emission significantly causes problems in achieving efficient performance. Power-dependent steady-state spectroscopy and ultrafast spectroscopic studies have been performed to understand the influence of Ag ions on ultrafast carrier dynamics and thermalization processes in colloidal CdSe NPLs. An ultrafast transient absorption spectroscopic study shows that the rise time is faster from 410 fs to ∼160 fs after 11% Ag doping in CdSe NPLs. The dopant states act as a trap for the charge carriers that facilitate faster relaxation of electrons in these dopant states. The bleach decay time constant (τ¹_r) changes from 5 ps to 800 fs, changing the dopant concentration from 0 to 11% Ag, indicating the charge carrier separation through an intra-band dopant-mediated state. Power-dependent steady-state photoluminescence spectroscopic study reveals that the thermalization rate reduces from 159.9 ± 9 mW K⁻¹ cm⁻² to 27.35 ± 2 mW K⁻¹ cm⁻² after Ag doping into CdSe NPLs due to the phonon bottleneck effect (PBE). Reducing the thermalization rate and charge carrier separation due to incorporating Ag dopant is beneficial for efficient optoelectronic devices.

中文翻译：

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Ag 离子掺杂胶体 CdSe 纳米片的功率依赖性和超快光谱研究


原子精确的二维 （2D） 半导体纳米片 （NPL） 因其优异的光学特性而被发现是下一代光电器件的有前途的材料。然而，声子发射造成的能量损失会显著导致实现高效性能的问题。已经进行了功率依赖性稳态光谱和超快光谱研究，以了解 Ag 离子对胶体 CdSe NPL 中超快载流子动力学和热化过程的影响。一项超快瞬态吸收光谱研究表明，在 CdSe NPL 中掺杂 11% Ag 后，上升时间从 410 fs 加快到 ∼160 fs。掺杂态充当电荷载流子的陷阱，促进这些掺杂态下的电子更快地弛豫。漂白剂衰变时间常数 （τ¹_r） 从 5 ps 变为 800 fs，掺杂剂浓度从 0% 变为 11% Ag，表明电荷载流子通过带内掺杂剂介导的状态进行分离。功率依赖性稳态光致发光光谱研究表明，由于声子瓶颈效应 （PBE），Ag 掺杂到 CdSe NPL 中后，热化速率从 159.9 ± 9 mW ^{K-1 cm-2} 降低到 27.35 ± 2 mW ^{K-1 cm-2}。由于掺入 Ag 掺杂剂而降低热化速率和电荷载流子分离有利于高效的光电器件。